// build steps:
// qmake -project "QT -= gui" "QT += sql"
// qmake
// make

#include <QtDebug>
#include <QCoreApplication>
#include <QDateTime>
#include <QThread>
#include <QSqlDatabase>
#include <assert.h>

void connectOk(const QString & connectionName)
{
    QSqlDatabase db = QSqlDatabase::database(connectionName);
    assert(db.isValid());

    db.setHostName("localhost");
    db.setDatabaseName("test");
    db.setUserName("root");
    db.setPassword("");

    bool result = db.open();
    assert(result == true);
    db.close();
}
void connectFail(const QString & connectionName)
{
    QSqlDatabase db = QSqlDatabase::database(connectionName);
    assert(db.isValid());

    db.setHostName("localhost");
    db.setDatabaseName("testaaaaaaaa");
    db.setUserName("root");
    db.setPassword("");

    bool result = db.open();
    assert(result == false);

    db.close();
}

class MyThread : public QThread
{
private:
    virtual void run()
    {
        const QString connectionName("bbb");
        QSqlDatabase::addDatabase("QMYSQL", connectionName);

//        connectOk(connectionName);
        connectFail(connectionName);

        QSqlDatabase::removeDatabase(connectionName);
    }
};

int main(int argc, char * argv[])
{
    QCoreApplication app(argc, argv);
    qDebug() << QDateTime::currentDateTime().toString(Qt::ISODate) << " Start";

    const QString connectionName("aaa");
    QSqlDatabase::addDatabase("QMYSQL", connectionName);

    connectOk(connectionName);
//    connectFail(connectionName);

    MyThread th;
    th.start();
    th.wait();

    QSqlDatabase::removeDatabase(connectionName);

    qDebug() << QDateTime::currentDateTime().toString(Qt::ISODate) << " The End";
    return 0;
}